This invention relates to an alloy composition suitable for use in making castings, and to a casting made therefrom.
In the past, a variety of nickel-based superalloys have been invented for use as casting materials, in particular for various uses in gas turbine engines. One such alloy is that claimed in our prior British Pat. No. 955016, this alloy being highly temperature and corrosion resistant and having been successful in its preferred application as a material for the cast nozzle guide vanes of gas turbine engines.
It is an unfortunate fact that the casting process does not always produce ideal results; thus for instance casting defects are sometimes found in cast superalloy objects. If this happens, it is clearly economical if the defects can be welded up rather than scrapping the faulty casting. Unfortunately the alloy mentioned above does not lend itself to the welding process and in consequence the repair of faulty castings and of articles damaged in service has been difficult.
In particular, like all alloys which are difficult to weld, the above-mentioned alloy is prone to cracking in the heat affected zone round the periphery of the weld.